Field of the Invention
The present invention relates to a driving force transmitting apparatus for transmitting a driving force to a unit detachably attachable to an image forming apparatus main body, and relates to an image forming apparatus including the same.
Description of the Related Art
In recent years, image forming apparatuses such as electrophotographic printers and copying machines have been desired to have improved operability. From a viewpoint of the improvement in operability, a cartridge system in which a photosensitive member and a process unit which acts the photosensitive member, such as a charging unit, a developing unit, and a cleaning unit, are integrally assembled into a cartridge and the cartridge is detachably attachable to an image forming apparatus main body has been employed. By using this cartridge system, operability is further improved, so that it became possible to easily perform maintenance of the above-described process unit such as the developing unit by a user himself/herself.
Similarly, an intermediate transfer body or the like of the image forming apparatus main body is also constituted as a unit and the unit is detachably attachable to the image forming apparatus main body so that operability and ease of maintenance are obtained.
Further, for a driving force transmitting apparatus for stably and reliably transmitting a driving force to these units detachably attachable to the image forming apparatus main body, a coupling pair formed by combining a projected portion and a corresponding recessed portion has been used. In this case, one of the coupling pair needs to be moved to be disengaged when the unit is detached from the apparatus main body. Conventionally, a configuration has been generally used in many cases in which in association with an operation of opening a cover which opens/closes the apparatus main body the coupling on the apparatus main body side moves in a rotation shaft direction so as to be separated from the coupling on the unit side and thereby connection of the coupling pair is released.
Japanese Patent No. 5559379 discloses a configuration of a coupling mechanism which is detachably attachable without using a linking mechanism with an opening/closing cover as described above.
On the other hand, a configuration in which the number of driving motors to be used is reduced as much as possible from a viewpoint of reduction in size and cost is employed for a driving mechanism of an image forming apparatus in many cases, and in such case, outputs from the motors serving as a driving source are divided by using a gear train and the like so that a plurality of outputs are performed. When controlling the plurality of outputs so as to individually drive or stop a part of outputs of, for example, a developing unit, a transfer belt, and the like, the driving motors are difficult to be stopped. Thus, a driving force is cut off by providing a clutch mechanism in some cases.
Japanese Patent No. 3884960 discloses one example of a specific configuration of a clutch mechanism in which an output shaft is difficult to be moved in a shaft direction.